Решите : 1. (tg α/ctg α) + 1 = 2. (sin^2 α - 1) / (1 - cos^2 α) =

Найдем значения выражения: 

1. (tg α/ctg α) + 1 = (sin a/cos a)/(cos a/sin a) + 1 = sin a/cos a * sin a/cos a + 1 = sin ^ 2 a/cos ^ 2 a + 1 = (sin ^ 2 a + cos ^ 2 a)/cos ^ 2 a = 1/cos ^ 2 a; 

2. (sin ^ 2 α - 1) / (1 - cos ^ 2 α) = (1 - cos ^ 2 a - 1)/(1 - (1 - sin ^ 2 a)) = - cos ^ 2 a/(1 - 1  + sin ^ 2 a) = - cos ^ 2 a/sin ^ 2 a = - ctg ^ 2 a.